Hitherto-known nanostructures containing carbon atoms include carbon nanotubes made of a cylindrically rolled two-dimensional graphene sheet.
Carbon nanotubes have high electrical conductivity, high mechanical strength, superior elasticity, heat resistance, and are lightweight. With these advantageous properties, carbon nanotubes are expected to be applied to various fields, including chemistry, electronics, and life science.
Carbon nanotubes can be produced through arc discharge, laser furnaces, chemical vapor deposition (CVD), and the like. However, these methods have a disadvantage in that they can only produce mixtures of carbon nanotubes of various lengths and diameters. The carbon nanotubes for the above usages are expected to be uniform in property; therefore, a method for selectively producing a carbon nanotube having a desired chemical structure has been strongly desired.
Recent studies reported research on a cycloparaphenylene compound, which is the smallest unit for making a carbon nanotube.
For example, Non-Patent Document 1 discloses a method for producing a cycloparaphenylene compound as a mixture having a cyclic structure composed of 9, 12, or 18 continuously bonded benzene rings, using 1,4-diiodobenzene and benzoquinone as materials.
Non-Patent Documents 2 and 3 disclose a method for producing a cycloparaphenylene compound having a cyclic structure in which 12 benzene rings are regularly bonded, using 1,4-cyclohexanedione and 1,4-diiodobenzene.
Non-Patent Document 4 discloses a method for producing a cycloparaphenylene compound in which 8 benzene rings are regularly bonded by reductive elimination of a biphenylene platinum square complex with bromine.
The cycloparaphenylene compounds disclosed in the above Non-Patent Documents have a cyclic chemical structure in which multiple phenylene groups are singly bonded. This structure has an interesting property as the smallest unit for making an armchair single-walled carbon nanotube (CNT).